Instant Payment Notification (IPN) is the method that PayPal uses to automatically notify a defined web page when a PayPal payment has been made. For a complete description refer to the PayPal IPN Manual which you can find on the http://www.paypal.com/ipn site.

The principle that PayPal uses is as follows : You first create a PayPal ‘buy now’ button and place it on your web page or create the buttons dynamically from a database. When someone clicks on your ‘buy now’ button, (or ‘proceed to checkout’ button in the case of a shopping cart system), PayPal posts data to the web page you defined during IPN set up. Your web page must then respond back to the paypal site.

After PayPal has confirmed the payment, it posts data back to your web page. Your web page then sends the data back to PayPal to act as a security handshake. Then PayPal will send ‘completed’ if payment has been correctly completed.

Once ‘completed’ has been received by your web page, you process the data in whatever way you want. The IPN method provides a relativly simple method of checking when a purchase has been made but remaining secure. The handshake principle of IPN makes it impossible to trick a web site that payment has been completed.

For digital goods, PHP-eSeller takes the IPN data from PayPal, carries out security checks to make sure the details are correct, then emails the purchaser with a username/password, all without any intervention by yourself. The purchaser is then able to login to a secure area where they can download their items.

The list of items which the purchaser sees does not have any urls as that could compromise the security. The list is made up of buttons which are then translated into filenames by PHP.

The purchaser only sees the files he has purchased and cannot access the file in any other way.

For physical goods the processing is not as complicated. It checks the details received from PayPal, sends a confirmation email to the purchaser if there are no problems, and stores the sales details in the database. Obviously, there is no login process required for physical goods.

It is this additional parameter that identifies vistors as coming from AdWords “google(cpc)” as apposed to organic “google(organic)”. The correct google cookie is then placed on to the

visitor machine. When a customer clicks on your AdWord, and then lands on your conversion page, you should see that that within the google(cpc) displays.

The key point is : Google Analytics cannot tell if the visitor came from an AdWords click if the gclid parameter is missing on the page that the user eventually lands on.

The key is to test whether your landing page retains the gclid parameter and this can be easily done as follows :

1. Take your destination URL (eg http://www.yoursite.com/landing_page.html) and paste it into your browser’s location bar (where you usually type in a web address)
2. Add a test parameter on to the end of the URL. If your URL does not already have parameters in it, append ?gclid=test. If there are already parameters, append &gclid=test on to the end. (For example, http://www.yoursite.com/landing_page.html becomes http://www.yoursite.com/landing_page.html?gclid=test; and http://www.yoursite.com/landing_page.html?myval=1 becomes)

http://www.yoursite.com/landing_page.html?myval=1&gclid=test
3. Press enter
4. Your browser will take you to your landing page. Be mindful of redirects, especially if you are tracking with Doubleclick, Atlas, etc tags.
5. Is the gclid=test parameter still visible in your browser’s location bar?
If yes, then auto-tgging should come through onto your landing page (providing that you have enabled auto-tagging on your account of course).

If no, there is most likely an intermediate redirect that is stripping out the gclid parameter.

1. First – change your destination URL to the ultimate page that the visitor lands on, thus bypassing any redirects
2. Configure your server so that the gclid parameter is passed along in the redirect

Other possible problems are that users are landing on a 404 error page, or that your landing page does not have the required google Anaytics Javascript code located on it.

If you want to track the PHP-eSeller template driven shopping cart pages using Google Anaytic Javascript code then the best place for the code is in the file ‘footer.htm’ which is located in the /templates/ folder.

Just make sure that the Javascript code goes between the <patTemplate:tmpl name=”footer”> and </patTemplate:tmpl> and not outsite of those tags.

You should be able to test it by just looking at the source of the shopping cart web page when you display it in the browser. You should see the Javascript code somewhere near the bottom of the page.

When you sell pin codes or software licence codes using PHP-KeyCodes, you may want the customer to enter in some text during purchase which is returned to you in the purchase information. This might be the type of cellphone, or some other information that you require for you records.

PayPal has a field called ‘custom’ which is a pass through field where any data entered into the field will be passed unchanged to PayPal and returned inside the IPN data.

In PHP-KeyCodes, entering text into the custom field is returned with the IPN payment details and the data is stored in the tblsaleshistory table along with all the other PayPal details and the purchased licence codes.

With the new Google tool you can search for any keyword or keyword phrase and see the estimated traffic.

The first column shows Advertiser Competition. The bar graph represents the number of advertisers that are bidding on each of the keyword phrase in you results. From this you can determine quickly whether a PPC Adwords campaign will require a high bid price and large budget.

If you are looking for a suitable hosting company, then Lunarpages.com is worth taking a look at. The Basic Plan is PHP/mySQL based, is competitively priced and in addition has unlimited storage and unlimited bandwidth. LunarPages.com

PHP-eSeller, PHP-SecureArea and PHP-KeyCodes all require a mySQL database and hence require a database username and password. Normally you will interact with the mySQL database using a control panel which will incorporate tools to easily create database and users. These facilities are provided by your web host and will be the best way to create database users.

However, with some web hosts it may be necessary to to create a user using myPHPAdmin.

To creating a user using the myPHPAdmin interface, asuming that you are logged in to myPHPAdmin with full previleges :